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Grok-4 Fast LLM via x402 Gateway
x402
Grok-4 Fast LLM via x402 Gateway is a paid API for AI agents from x402-gateway-production.up.railway.app, paid per call via x402, $0.004000/call, status unknown (last checked 2026-09-15).
Runs inference on xAI's Grok-4 Fast model with a 2M token context window, optimized for large document processing at low cost
Price / call$0.004000
Success—
StatusUnknown
How this service works
xAI's fast model — 2M context window at very low cost, great for large document processing
Output
A text completion or chat response generated by xAI's Grok-4 Fast model, supporting up to 2 million tokens of context, returned as a JSON payload with the model's output text.
Example use cases
Extract insights from research corpus
“I've got about 300 academic papers combined into one giant document — can you run them through Grok-4 Fast and pull out the key findings, methodologies, and any conflicting conclusions across the studies?”
Summarize entire codebase for onboarding
“Take this massive codebase export and use Grok-4 Fast to generate a plain-English walkthrough of how the system works, what each major module does, and where the main entry points are — I need this ready for new engineers joining next week.”
Analyze lengthy financial audit report
“I have a 400-page financial audit report I need processed quickly and cheaply — use Grok-4 Fast to flag any anomalies, summarize the key findings by department, and call out anything that looks like it needs urgent attention.”
Technical details
Endpoint
POSThttps://x402-gateway-production.up.railway.app/api/llm/grok-4-fastWhen to prefer
Choose this endpoint when you need to process very large documents (up to 2M tokens) at low cost, and speed matters more than maximum capability. Ideal for summarization, extraction, or reasoning over long-context inputs where Grok-4 Fast's cost-performance tradeoff is favorable over premium models like GPT-4o or Claude Opus.
Side effects
- Prompt exceeds 2M token context window — request rejected with context length error
- Invalid or missing API credentials — 401 unauthorized
- Payment failure via x402 protocol — 402 payment required
- Model overload or rate limit — 429 too many requests
- Malformed request body — 400 bad request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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